Blue-Emitting K₂Al₂B₂O₇:Eu²⁺ Phosphor with High Thermal Stability and High Color Purity for Near-UV-Pumped White Light-Emitting Diodes

Abstract

Novel blue-emitting K2Al2B2O7:Eu(2+) (KAB:Eu(2+)) phosphor was synthesized by solid state reaction. The crystal structural and photoluminescence (PL) properties of KAB:Eu(2+) phosphor, as well as its thermal properties of the photoluminescence, were investigated. The KAB:Eu(2+) phosphor exhibits broad excitation spectra ranging from 230 to 420 nm, and an intense asymmetric blue emission band centered at 450 nm under λex = 325 nm. Two different Eu(2+) emission centers in KAB:Eu(2+) phosphor were confirmed via their fluorescence decay lifetimes. The optimal concentration of Eu(2+) ions in K2-xEuxAl2B2O7 was determined to be x = 0.04 (2 mol %), and the corresponding concentration quenching mechanism was verified to be the electric dipole-dipole interactions. The PL intensity of the nonoptimized KAB:0.04Eu(2+) phosphor was measured to be ∼58% that of the commercial blue-emitting BaMgAl10O17:Eu(2+) phosphor, and this phosphor has high color purity with the CIE coordinate (0.147, 0.051). When heated up to 150 °C, the KAB:0.04Eu(2+) phosphor still has 82% of the initial PL intensity at room temperature, indicating its high thermal stability. These results suggest that the KAB:Eu(2+) is a promising candidate as a blue-emitting n-UV convertible phosphor for application in white light emitting diodes.

Identifying an efficient, thermally robust inorganic phosphor host via machine learning

“…Similarly, NaSrBO 3 :Ce 3+ and NaCaBO 3 :Ce 3+ both have a reported Φ of ≈75% 38,39 . Many of the borate phosphors including K 2 Al 2 B 2 O 7 :Eu 2+ are also thermally robust showing minimal loss of luminescence at high temperature 40 . Although the search for borate phosphors is directed based on the machine-learning algorithm, the discovery of these materials was still achieved through traditional means including isovalent substitution of known materials, rationally searching phase space, or through serendipitous discovery.…”

Extra-Broad Band Orange-Emitting Ce3+-Doped Y3Si5N9O Phosphor for Solid-State Lighting: Electronic, Crystal Structures and Luminescence Properties

“…[1][2][3][4][5] Solid-state white light-emitting diodes (w-LEDs) are superior to traditional incandescent lamps and fluorescent tubes in terms of long lifetime, excellent reliability, high luminous efficiency and low energy consumption . [6][7][8] Currently, phosphor-converted white LEDs are recognized as the main modus for solid state lighting, which are fabricated by combining either an ultraviolet (UV, 350-420nm) or blue (450-470nm) LED chip with phosphors.…”

A white-light emitting phosphor LuNbO4:Dy3+ with tunable emission color manipulated by energy transfer from NbO43− groups to Dy3+

“…acquired above implies the little possibility of exchange interaction because it can be prevailing only for about 5 Å[32,33]. Another mechanism of radiation reabsorption becomes dominant only as the fluorescence and absorption spectra are widely overlapping, which also does not intend to occur in this case.…”